Clutch mechanism



Aug. 31, 1937. H. D. COLMAN CLUTCH MECHANISM Filed Sept. 7, 1934 4 Sheets-Sheet. l

ATTORNEYS Aug. 31, 1937. H. D. COLMAN CLUTCH MECHANISM Filed Sept. 7, 1934 4 Sheets-Sheet 2 INVENTOR Howard D. Colman BY M ATTORNEYS Aug. 31, 1937. H. D. COLMAN CLUTCH MECI-{ANISM Filed Sept. 7, 1934 4 Shasta-Sheet 3 56 INVENTOR Howard D. Colman M x 3'4 ATTORNEYS Aug. 31', 1937.

H. D. COLMAN 2,091,270

CLUTCH MECHANISM Filed Sept. 7, 1934 4 Sheets-Sheet 4 b a INVENTOR Howard D. Colman BY 9W x M,

ATTQRNEYS Patented Aug. 31, 1937 UNITED. STATES PATENT OFFICE The present invention relates to a new and improved clutch mechanism.

One of the objects of the invention is to provide a novel clutch mechanism having a main clutch, a pilot clutch, and an end face ball cam actuator operable by the pilot clutch to actuate the main clutch.

Another object resides in the provision of a new and improved clutch mechanism having a main clutch and an electromagnetic pilot clutch with a stationary exciting coil for actuating the main clutch.

A further object isto provide a novel clutch mechanism having a friction disk clutch, an end thrust ball bearing and an end face ball cam actuator reacting against the bearing to close the clutch, and in which the balls of the bearing and the actuator permit a universal rocking movement of the clutch elements so that pressure is imparted equally to the balls and applied uniformly to the clutch elements regardless of mechanical irregularities;

A more specific object resides in the provision of a novel end face'ball cam clutch actuator which is simple and inexpensive in construction, which is sensitive, efiicient and powerful in action, which is substantially frictionless, which is automatically reversible under a comparatively light axial pressure, and which is self-adjustable to maintain the balls in proper position.

Still another object resides in the provision of a friction disk clutch normally open under the influence of a spring, and new and improved means for automatically adjusting the clutch to compensate for wear, whereby the spring is required to work only through the opening and closing range of the clutch and not through the wear range, and hence is causedto maintain a substantially uniform pressure under all conditions and degrees of wear.

A further object is to provide a novel electromagnetic friction disk clutch, with a stationary exciting coil, having flux transfer gaps which serve also as gaps for eliminating residual magnetism, and are of a low density so as to require a relatively low current input to operate the .clutch, and having pole faces in direct and constant rubbing engagement.

Other objects reside in the provision of an electromagnetic friction clutch having new and improved means for automatically compensating for wear, and having novel means for ventilating the friction surfaces and cooling the magnet coil.

Other objects reside in the provision .of novel means for lubricating the ball cam actuator,

and means for preventing lubricant from reaching the friction surfaces of the clutches.

Further objects and advantages will become apparent as the description proceeds.

In the accompanying drawings, Figure 1 is an axialsectional view taken along line l-l of Fig. 5 of a clutch mechanism embodying the features of my invention.

Fig. 2 is a transverse sectional view taken substantially along line 2-2 of Fig. 1, and illustrating a self-adjusting mechanism for compensating for wear on the friction surfaces of the main clutch.

Fig. 3 is a perspective view of a disk forming part of the pilot clutch.

Fig. 4 is a fragmentary transverse sectional view on a reduced scale taken along line 4-4 of Fig. 1, and illustrating a friction ring forming part of a self-adjusting mechanism for compensating for wear on the friction surfaces of the pilot clutch.

Fig. 5 is a transverse sectional view of the clutch mechanism taken along line 5-5 of Fig. 1.

Fig. 6 is a fragmentary axial sectional view, taken along line 6-6 of Fig. 5, and illustrating the ball cam actuator for the main clutch.

Fig. "I is a fragmentary sectional detail view taken along line '|-l of Fig. 6 and illustrating the end thrust bearing for the ball cam actuator.

Fig. 8 is a perspective view on an enlarged scale of the end plates of the pilot clutch and the cage in which they are supported.

Fig. 9 is a perspective view, on an enlarged scale, of a movable end plate, a spline sleeve, the wear adjuster and tie bars forming part of the main clutch.

Fig. 10 is a perspective view of a spring pawl illustrated in Fig. 2.

Fig. 11 is a fragmentary axial sectional view.

of the pilot clutch, and illustrating the path of flux.

Figs. 12 and 13 are partial transverse sectional views taken respectively along lines |2--I2 and 13-43 of Fig. 1.

Figs. 14 and 15 are sectional views respectively showing two different forms of the ball cam actuator in development.

Referring more particularly to the drawings, the clutch mechanism constituting the exemplary embodiment of the invention comprises a main clutch l6 for connecting two elements I! and II, a ball cam actuator I 9 for closing the main clutch, and a pilot clutch 20 for operating the actuator.

The elements I! and It may assume various other.

forms depending on the different environments in which the clutch mechanism is to be used. Either of the elements l1 and I8 may be connected to a source of power (not shown) to drive the In the present instance, the element I1 is shown as a shaft extending substantially through the clutch mechanism, and designated for convenience as the driven element. The other element 8, correspondingly designated as 10 the driving element, consists of a circular plate which is rotatably supported by the shaft l1 and which is formed externally with a power in- .let gear 2|. Preferab1y,'a ball bearing 22 is interposed between the shaft I1 and the plate l8. The plate I8 is provided on one side at its outer periphery with an annular coaxial flange 23 which encloses the main clutch I6, and forms part of a housing enclosing the major portion of the clutch mechanism. A cylindrical cage 24-, constituting another section'pf the housing, has an outer peripheral flange 25 on one end at tached to the free end of the flange 23, and has an inner peripheral flange 26 on the other end. A cover plate 21 secured to the flange 26 is ro- 25 tatably mounted by means of a ball bearing 28 on a reduced extension 29 of the shaft |1. It will be evident that the plates l8 and 21 constitute the end walls of thehousing. To prevent the escape of lubricant from the housing 30 along the shaft l1, suitable seal rings 30 and 3| are inserted respectively in the inner peripheral 1 surfaces of the plates l8 and 21.

The main clutch |6 (see Fig. 1) may be provided in various forms, but is herein shown as of the twin disk type, comprising two intermediate disks 32 and 33 connected to the driving 5 element l8, and alternately arranged between two end 'plates 34 and 35 and an intermediate disk 36 connected to the driven element l1. Annular friction rings 31 are secured respectively to opposite sides of the'disks 32 and 33. To establish their connection with the driving element l8, the disks 32 and 33 are formed in their outer peripheries with a plurality of teeth.

38 which slidably inter-fit with a plurality of uniformly peripherally spaced longitudinal spline keys 39 formed in the innerperiphery of the flange 23.

The end plate 34 is formed on a parallel axially ofiset flange 40 which is integral with one end of an elongated sleeve 4| axially splined on the shaft l1 within the clutch housing, and which defines therewith an annular recess42. A nut 43 threaded onto the reduced shaft extension 29 against the other end of the sleeve 4| serves to hold the flange 40 against a peripheral shoulder 44- on theshaft |1.. Hence, the end plate 34 is axially stationary. 'The' other end plate 35 is mounted for axial movement by means of inter- 60 nal teeth 45'slidably interfltting with a plurality of longitudinal spline keys 46 on the sleeve 4|, and is formed on its inner side-with an annular coaxial sleeve 41 extending through the intermediate disks 32, 33 and 36 and through the stationary end plate 34 into freely disposed relation in the recess. 42. The intermediate disk 36 has internal teeth 48 slldably interfitting with longitudinal spline keys 49 on the sleeve 41.

. A coiled compression spring 50 disposed within the sleeve '41 tends to separate the plates 34 and 35 and thereby to open the main clutch l6. One end of the spring 50 abuts against the inner side of the movable plate 35, and the other end bears against a ring 5| anchored relatively to the sleeve 4|. The ring 5| seats against a series of lugs 52 struck outwardly respectively from the adjacent ends of a plurality of the tie bars 53. These bars are slidably mounted in longitudinal grooves 54 formed in the sleeve 4| between certain of the keys 46, and extend through a ring 55 opposed. to the ring 5|. A series of lugs 56 are struck outwardly respectively from the ends of the bars 53 to engagea ring 51 bearing frictionally against a nut 51 adjustably threaded on the outer end of the sleeve 4|.- Additional intermediate lugs 56 are struck out: wardly from the bars 53 and engage in notches 55 in the ring 55. The ring 55 is splined for axial movement on the sleeve 4| by means of internal teeth 58 interfitting with the keys 46, and seats against the nut 51. The .ball cam actuator l9, which includes the ring 55, is disposed about the sleeve 4| between the movable end plate 35 and the nut 51. Hence, by reason of the confining action of the lugs 52 and 56 and the pressure of the spring 50, the rings 5| and 55 are always located in a predetermined spaced relation.

The ball cam actuator 9 (see Figs. 6, 7, 12, and 13) is operable to exert an axial thrust on the movable plate 35 against the action of the spring 50 to close the main clutch l6. In its preferred form, the actuator |9 comprises a sleeve 59 of non-magnetic material rotatably encircling the sleeve 4|, and formed on its inner periphery with a flange 60. 'The ring 55 and the flange 60 constitute opposed respectively fixed and movable end face ball races between which two balls 6| spaced 180 apart are inserted (see Figs. 6 and 7). Preferably, two hardened blocks or inserts 62 are mounted in recesses 63 in the inner end face of the ring 55, and two'similar blocks 64 are mounted in recesses 65 in the opposed face I opposed grooves or raceways 66 and 61 arcuate about the axis of the shaft H for rolling engagement by the balls 6|; Oppositely facing stop shoulders 68 and 69 are provided respectively at the adjacent ends of the grooves 66 and 61 for engagement by the balls 6| when the actuator l9 is in idle position. The stop shoulders 68 and 69 may be provided in any suitable manner, and are herein shown as formed in the material of the ring 55 and the flange 60 and inclined to the path of. the balls 6| in order to eliminate shock when the actuator I9 is returned into idle position. Thus, the flange 60 constitutes a thrust collar for the actuator |9 adapted to rock about a transverse axis passing through the balls 6|.

A ring 19, mounted in the left end of the sleeve 59 in opposed relation to the flange 60, bears axially against an annular flange 1| on the end plate 35. The ring 10 has internal spline teeth 1|] engaging the keys 46, and hence is rotatable with the sleeve 4|. A cap nut 13 threaded onto the left end of the sleeve 59"substantia1ly encloses the ring10. The ring 10 and the flange 60 constitute respectively fixed and movable end face ball cam races between which two balls 14 are inserted. The balls 14 are spaced 180 apart, and are spaced 90 from the balls 6 I. Two'hardened blocks or inserts 15 are mounted in recesses 16 in the left hand face of the flange 69, and two similar blocks 11 are mounted in recesses 18 in the opposed face of the ring 10. The blocks 15 and 11 are staggered endwise, and are formed respectively with opposed cam grooves or race ways 19 and arcuate about and similarly ingagement by the balls '14. Inclined stop shoulders 8| and 82 are formed in the flange 69 and the ring 18 at the deep ends of the cam grooves 19 and 89 to locate the balls 14 when the actuator is in idle position. It will be evident. that the ring 10 and hence the movable clutch plate' are adapted to rock about a transverse axis passing through the balls 14 and extendin perpendicularly to the axis through the balls 8|.

When the clutch actuator I9 is in zero or idle position, i. e. when the main clutch H3 is open, the four balls 6| and 14 are respectively in engagement with the shoulders 68, 69, 8|, and 82. Upon rotation of the sleeve 59 out of the idle position, shown in Fig. 6, the balls 14 will roll along the cam grooves 19 and 88 to close the main clutch l6 against the action of the spring 58. Since the sleeve 59 and the ring 18 are adapted to rock respectively about two mutually perpendicular axes, the pressure is distributed equally between the balls regardless of slight inaccuracies that may be present in the coacting parts, and

the pressure of the end plates 34 and 35 on the friction rings 31 is balanced. A slight clearance is provided between the sleeve 41 and the end plate 34, the teeth 45 and the spline keys 46, andthe sleeve 59 and other relatively movable parts to'perrnit such self-compensating movement.

When the sleeve 59 is released, the spring 58 acting through the cam grooves 19 and 80 serves to return the parts to initial position. The shoulders 68, 69, 8 I, and 82 act as bumpers for the balls BI and 14 to prevent injury thereto upon impact at the end of the clutch opening movement. The impact is minimized by reason of the inclination of the shoulders which imparts cam characteristics thereto permitting the actuator slightly to overrun its idle position in the opening movement. If the balls GI and 14 should slip slightly relative to the coacting grooves 68, 61, 19, and 80, they will be reestablished in correct position through coactioh with the inclined shoulders at the end of the opening movement. Hence, the angular spacing of the balls 5| and 14 is substantially maintained.

The shape of the camgrooves 19 and 88 may be varied to impart different characteristics to the ball cam actuator l9. Thus, in the development shown in Fig. 15, the grooves 19 and are formed, 1. e. have a variable angle, and hence a variable force multiplying factor. In the pres ent instance, the initial portion a of each of the cam grooves 19 and 88 has a steep angle, and the final portion 1) has a slight angle.

The formed cam grooves 19 and 80 are advantageous where the actuator I9 is intended only to close and open the clutch. Thus, during the initial closing movement when the required closing pressure is relatively low, the'steep portions a afford adequate power. These portions are formed to overcome the pressureof the spring 58. During the final closing movement when the power requirements are substantially increased,

the low-angle portions b are operative. Thus, the.

graduated slope of the cam grooves 19 and 88 increases the available power as the spring pressure and the clutch pressure is increased, and decreases the required extent of rotation of the actuator l9. Because of the reduced'force and extent of movement initially imparted thereto,

the actuator I9 is operable at a decreased velocity, and hence will not overrun. The substantial angle of the initial cam portions a also causes the spring 58 to hold the actuator l9 firmly in idle position.

In the modified development illustrate Fig. 14, the cam grooves 19 and 80 are straight, and have a constant force multiplying factor. This shape is advantageous where it is desired to obtain a graduated control of the clutch pressure, as for example by varying the excitation of an electromagnetic clutch by adjustment of a rheostat (not shown) to operate the actuator l9. If the cam grooves were to be substantially graduated or formed, the minimum rheostat adjustment for the initial steep portions would be too high for the final low-angle portions.

Wear on the friction rings 31 of the main clutch I6 is automatically compensated. The means for this purpose in its preferred form (see Figs. 1, 2 9 and 10) comprises the nut 51 which is formed in its outer periphery with an annular groove 83 defining two parallel circumfer ential ridges 84 and 85 formed with ratchet teeth 85. A split band spring 81 is inserted in the groove 83, and is bent outwardly and enlarged at one end to provide a spring pawl 88 adapted for engagement with both series of teeth 85. An arm 89 projects laterally from one side of the pawl 88, and is formed on its free end with oppositely extending curved fingers 90 and 9|. Secured to the inner periphery of the right end of the sleeve 59 is a circular split spring 92 held in position by dowels 93. The ends of the spring 92 are formed respectively with two spaced inwardly projecting lugs 94 and 95 located at opposite sides of the arm 89 and adapted for engagcment respectively with the fingers 99 and 9|. The stops 94 and 95 are V-shaped to engage the fingers 98 and 9| at an angle, and thereby to avoid shock. A flange nut 96 threaded onto the right end of the. sleeve 59 serves to enclose the pawl and ratchet mechanism.

The parts are shown in Fig. 2 in their idle position normally occupied when the main clutch I5 is open. In closing the clutch IS, the sleeve 59 isrotated in a counterclockwise direction as indicated by the arrow. If the clutch I5 is properly adjusted, the sleeve 59 will be rotated until the lug 94 engages the finger 90, but not enough to move the latter or the pawl 88 through the distance of one ratchet tooth 86. In the opening movement, the lug 95 will engage the of rotation of the sleeve 59, exceeds the distance of one tooth 86, the pawl 88 will engage a new tooth. In the succeeding opening movement of the clutch Hi, the lug 95 will cause the pawl 88 to rotate the nut 51, through the distance of one tooth, thereby reducing the spacing between the ring 55 and the fixed end plate 34. By reason of the foregoing construction, the spring 50 is required only to work through the clutch opening and closing range and not through the aggregate range of wear, and therefore is maintained at a constant operating pressure regardless of wear on the friction rings 31. When the clutch H5 is used with a ball cam actuator I9, as herein shown, the cam grooves 19 and 80 can have an angle more gradual than would otherwise be feasible, and can be graduated or shaped to greater advantage.

The flange 50 and the end caps 13 and 96 define two oil pockets for the two sets of balls 6| and 14. These pockets are filled with a suitable lubricant. When the clutch I6 is running, the lubricant is distributed by centrifugal force in a thin layer on the inner peripheral surface of the sleeve 59. The balls 6I and 14 dip into this 1 film, thereby assuring lubrication of the balls and their races.

Within certain aspects of the invention, the pilot clutch 20 may be provided in any desired form. However, the pilot clutch 20 preferably is of the electromagnetic type with a stationary exciting coil 91 which is especially suitable in the compound clutch mechanism herein disclosed. The pilot clutch 20 of the foregoing type is operable with a relatively low current consumption and under all load conditions of the main clutch I6 to satisfy the relatively low force requirements of the force multiplying actuator I9, and at the same time is inexpensive in construction, not subject to operating troubles commonly encountered, and long lived in operation. Thus, the coil 91 requires no contact slip rings or brush mountings, and hence avoids the necessity for maintaining these parts and correcting contact difiiculties. The coil 91 need not be protected against the 25 clutch pressure, and is located out of thermal contact with the high temperature parts. N voltage drop, with attendant loss of power, such as occurs at the brush contacts in other types of electromagnetic clutches, is possible.

The coil 91 consists of two annular sections rigidly mounted in axially spaced relation concentrically about the cage 24 within a supporting ring 98, and defining an intermediate air space 99 for ventilation. 'A plurality of peripherally spaced apertures I00 in the ring 98 open to the space 99. Secured to the opposite ends of the ring 98 are two angle-shaped rings MI and I02 of magnetic material, the rings IOI and I02 having spaced oppositely extending legs I03 and I04 40 projecting axially into the coil sections, and constituting flux transfer poles.

The cage 24 (see Fig. 8) comprises a plurality of uniformly peripherally spaced longitudinal bars I of non-magnetic material connecting the flanges 25 and 26. Mounted within the cage 24 and the coil 91 about the sleeve 59 for relative axial movement are two ring-shaped end plates I06 and I01 formed with transverse notches I00 slidably receiving the bars I05, and hence constrained to rotate with the driving member I8. The plate I06 is movable axially, and the plate I01 is positioned against the cage flange 26. P0- sitioned in direct contact against the adjacent side faces of the end plates I06 and I01 are two annular, armature disks I09 and H0. Each of these disks is connected for rotation with the driving member I8 by means of radially projecting lugs III engaging opposite sides of the cage bars I05. Two annular rings II 2-and H3 defining working pole faces I I4 and H5'on their adjacent ends snugly encircle the disks I09 and H0, and are connected for rotation therewith through interfitting engagement with the lugs III. An intermediate disk H6 is positioned between the rings H2 and H3 in direct bearing engagement adjacent its outer periphery with the pole faces I I4 and H5, and is formed in its inner periphery with a series of notches H1 slidab'ly engaging a plurality of longitudinal spline keys H8 on the exterior of the sleeve 59. Radial ventilating grooves II 6 (see Fig. 3) are formed in opposite sides of the disk I I6, the grooves on one side being staggered with respect to those on the other side. Secured to the adjacent sides of 7 the disks I09 and H0 and spaced inwardly-from the pole rings H2 and H3 are two friction rings H9 and I20 in bearing engagement with oppo-- site sides of the disk II 6. Two annular grooves I2I and I22 are formed in opposite sides of the disk H6 in registration with the spaces between K the rings H2 and H3, and H9 and I20 to provide air gaps.

It will be evident that all of the members posi- The path of flux is indicated by the arrows in Fig. 11, and comprises a circuit through the transfer pole I03, the end plate I06, the pole ring H2, the disk H6, the pole ring H3, the

end plate I01, the transfer pole I04, and the rings I02, 98 and NH. Since the working pole faces H4 and H5 are in direct contact with the disk H6, the metallic flux circuit is interrupted only by two relatively small air gaps I23 and I24 between the transfer poles I03 and I04 and the end plates I06 and I01. The transfer poles I03 and I04 and the opposed surfaces of the end plates I06 and I01 provide a transfer area which is very large in relation to that of the working pole faces H4 and H5. Since the flux density varies inversely as the square of the area, lateral pull onthe end plates I06 and I01 is materially reduced, and hence any tendency of the plates to depart from true concentricity with the transfer poles I03 and I 04 is substantially avoided. The air gaps I 23 and I24 are necessary to provide a mechanical separation between the fixed and movable parts of the clutch 20, but are utilizedto serve two purposes. Thus, the gaps I 23 and I24 serveas transfer gaps and also as interruptions to eliminate residual magnetism. They are of suffi cient radial width to provide adequate clearance between the transfer poles I03 and I04 and the end plates I06 and I01, regardless'of any slight eccentricity that may develop or any slight manufacturing inaccuracies that may exist, and still have but a relatively small magnetic reluctance.

The pole faces H4 and H5 are adapted for direct rubbing contact with the disk H6. When the coil 91 is energized the end plate I06 is attracted through a small range to increase the bearing pressure to close the clutch 20. No substantial air gap and no spring pressure need be overcome, and hence the force requirements for closing the clutch 20 are relatively low and practically constant. As a result, the clutch has a high rating for a given size and current input, and is subject to a finely graduated control.

Wear on the. disk I I6, the pole faces H4 and I I5 and the friction rings H9 and I20 will not vary the force requirements. The friction rings H9 and I20 will wear in use, but will cause little. wear on the contacting areasof the disk H6;

The pole faces I I4 and I I5 and the areas of the disk H6 contacting therewith will wear substantially equally, and hence these areas of the disk will recede inwardly. However, by reason of the air gaps I 2I and I22, peripheral contact between therings H2 and H3 and the disk H6 will not be established, and hence the contacting pole areas will remain constant in size, and no loss of flux will be suffered.

2O permitted by the groove I26.

Means is provided to limit the extent to which the end plates I06 and IN can separate when the closing pressure of the pilot clutch 20 is released, and to maintain the distance constant regardless of wear on the friction rings H3 and I20. This means (see Figs. 1 and 4) comprises a circular split spring I25 which is seated in an annular groove I26 in the periphery of the end plate I06, and which acts resiliently against the inner'surfaces of the cage bars I05 to provide a frictional drag. A pin I21 projects inwardly from one of the bars I05 between the ends of the spring I25 to retain the ends in position beneath this bar. The groove I26 is slightly greater in width than the spring I25. The. frictional drag of the spring I25 on the cage, bars I05 is suflicient to prevent displacement of the spring when the clutch is opened, and hence limits the movement of the end plate I06 to the smallplay As wear occurs on the clutch friction surfaces, the closing movement of the end plate I06 acts to adjust the spring I against the frictional drag a corresponding extent. The motion of the end plate 25 I06 does not include the wear range sothat the clutch can be worn down completely while maintaining its low force requirements.

When theelectromagnet is deenergized to remove the closing force on the pilot clutch, the clutch elements are self-acting by reason of the rubbing action therebetween to effect a minute separation suiiicient for release, but this separation is not necessarily as great as, and in any event is limited to, the maximum range detert5 mined bytheclearance between the sides of the ring I25 and the groove I26. Since no means is provided for urging the clutch elements apart, they tend to remain substantially in contact but without a gripping pressure when released since a slight resistance to movement is set up by the inertia. of the parts and the spline connections with the bars I05. 6

Lubricant is prevented from reaching the friction surfaces of the clutches I6 and 20. Any lubricant passing along the sleeve 4| into the main clutch I6 is prevented irom' reaching the friction surfaces by the sleeve 41, and is directed into the recess 42 from where it is discharged by centrifugal force through suitable openings I28 in the flange 40. On leaving the openings I28, the lubricant is directed by a conical baflle I29 to suitable openings I30 in the plate I8. Lubricant finding its way into the space between the clutches I6 and 20 is directed by the action of centrifugal force across conical overlapping baffle flanges I3I and I32 on the end plates 35 and I06 through openings I33 discharging to the spaces betweenthe cage bars I05. Openings I34 are provided in the flange 25 to discharge anylubri- 6O cant that may enter the space to the right of the clutch 20.

The operation of the clutch mechanism will be evident from the foregoing description, and briefly summarized is as follows: Normally the actuator I9 occupies its idle or rest position illustrated in Fig. 6 in which it is'held by the pressure of the spring 50.. When the coil 91 is energized, the pressure in the pilot' clutch 20 is increased sufficiently to rotate the actuator I9 in a 7 counterclockwise direction as viewed in Fig. 2. Thereupon, the balls I4 coacting with the cam grooves I9 and will actuate the end plate 35 I to close-the main clutch I6. If the cam grooves 19 and 80 are graduated or formed as illustrated .15 in Fig. 15, the initial force will be comparatively low, and the final force will be comparatively heavy. Upon deenergizing the coil 91, the axial thrust of the spring 50 will reverse the operation of the actuator I9, thereby returning the parts to their initial positions. Wear in the main clutch 5 I6 is compensated through automatic adjustment of the nut 51 which serves to advance the actuator I0 andplate'35 toward the plate 34. Wear in the pilot clutch 20 is also automatically compensated to, maintain a constant range of open- 10 ing and closing movement.

I claim as my invention:

1. A clutch mechanism comprising, in combination, a main clutch having a relatively large capacity and having a plurality of relatively axi- 1 ally movable clutch elements, a force-multiplying: rotary camactuator for closing said clutch by forcing said elements axially into engagement, and an electromagnetic clutch having a stationary exciting coil enclosing driving and driven a friction elements for operating said actuator to close said main clutch.

2. A clutch mechanism comprising, in combination, a shaft member, a coaxial member, an

elongated sleeve fixed on said shaft member, co- 2:

acting relatively axially adjustable frictionclutch elements secured for rotation respectively with said members and including two end elements, one of said end elements being fixed on said sleeve and defining an annular recess, the other 3| of said end elements being movable along said sleeve and having a coaxial sleeve extending through the remaining elements into said recess,

a stop fixed on said sleeve outside of the movable end element, a stop between said end elements in 35 fixed relation to said first mentioned stop, a coil ,compression spring between said sleeves and abutting at opposite ends against said movable element and said last mentioned stop, axially extensible means disposed in end abutment with 40 said first mentioned stop and said movable element, and means for operating said extensible means to move said elements into frictional engagement.

3. A clutch mechanism comprising, in combi- 45 nation, a clutch having a plurality of elements movable axially into and out of engagement, an end face ball cam actuator for said clutch and having only two balls spaced 180 degrees apart, an end thrust ball bearing reacting against the 50 pressure of said actuator on said clutch, and having only two balls spaced 180 degrees apart and degrees from said first mentioned balls, and means for operating said actuator.

4. A clutch mechanism comprising, in combi 5 nation, a clutch having a plurality of elements including an end actuating element movableaxially into and out of engagement, a stop spaced axially from said clutch, an end thrust ball bearing positioned against said stop and having 50 only two balls spaced degrees apart, and an end face ball cam clutch actuator operatively disposed coaxially between said actuating element and said bearing and having only two balls spaced 180 degrees apart and 90 degrees from 5 said first mentioned balls, and means for operating said actuator.

5. A clutch mechanism comprising, in combination, a shaft member, a plate member rotatable on said shaft member and having an annular v7o sleeve, a sleeve keyed to said shaft member, a plurality of coaxial friction clutch elements alternately secured for rotation respectively with said members, one end element being fixed on said last mentioned sleeve,'the other of said ele- 1| ments being free for axial movement, the other endvelementshaving a coaxialfsleeve extending through the intermediate elements, a coiled comto said shaft, a plurality of coaxial friction clutch' elements alternately secured for rotation respectively with said members, one end element being fixed on said last mentioned sleeve and defining an annular recess therewith, oil passages opening through said end element for directing oil from said recess to said bafile means, the other of said elements being free for axial movement, the other end element having a coaxial sleeve extending through the intermediate elements into said recess, a coiled compression spring interposed between said last two mentioned sleeves and tending to separate said end elements, and means for moving said elements into engagement.

'7. A clutch mechanism comprising, in combination, a shaft member, .a plate member rotatable 80 on said shaft member and having an annular sleeve, a sleeve keyed to said shaft member, a plurality of coaxial friction clutch elements alternately secured for rotation respectively with said members, one end element being fixed on 85 said last mentioned sleeve and defining an annular coaxial recess, the other of said elements being free for axial movement, the other end element having a coaxial sleeve extending loosely into said recess and being free for a limited universal rocking movement, acoiled compression spring interposed between said last two mentioned sleeves and tending to separate said elements, and means for exerting an axial thrust on said other element to move said elements into 5 engagement, said means being freely universally adjustable for self adaptation to the position of said other element.

- 8. A clutch mechanism comprising, in combination, a shaft member, a second member ro- 50 tatable about said shaft member, a plurality of driving and'driven friction clutch elements'secured respectively for rotation with said members and movable axially into and out of engagement, a sleeve fixed on said shaft member and rigid 35 with one end element, a nut adjustably threaded on said sleeve, a stop encircling said sleeve between the end elements, a plurality of tie barslongitudinally slidable along said sleeve and limiting the spacing of said nut and stop, a coiled i0 compression spring encircling said sleeve and interposed between the other end element and said stop, an axially extensible cam actuator seating against said nut and acting against said other element, and means for automatically adjusting is said nut to compensate for wear on said elements.

9. An electromagnetic clutch comprising, in combination, coaxial driving and driven members, two coaxial end face clutch elements mount- 0 ed for relative axial movement into and out of coacting engagement and for rotation respectively with said members, an annular friction facing secured on one of said elements for engagement with'the other of said elements, an an- I nular pole projection on said one element in concentrically spacedrelatio'n about said facing and having a pole face for direct engagement with said other element, and a stationaryelectromagnet for effecting engagement of said elements.

10.'A n electromagnetic clutch comprising, in 5 combination, coaxial driving'and'driven members, two coaxial end face clutch elements mounted for relative axial movement into and" out of coacting engagement and for rotation respectively with said members, an annular fric-- 10. tion facing secured on one of said elementsfor engagement with the other of said elements, an annular pole projection onsaid one element in concentrically spaced relation about said facing and having a pole face initially flush with the 15 friction surface of said facing for direct rubbing engagement with said other element, an annular groove in said other element opposite the space between said facing and said pole projection, and an electromagnet for effecting engagementv 20 between said elements.

11. An electromagnetic clutch comprising, in combination, coaxial driving and driven members, two-coaxial end face friction clutch elements mounted for relative axial floating movement into and out of engagementand for rotation respectively with said members, andhav-;, ing pole faces adapted for direct rubbing engagement, and an electromagnet encircling said elements and for effecting engagement of said 30 elements, whereby said elements are separable upon deenergization of said electromagnet solely in response 'to release of the'pressure of clutch engagement.

12. An electromagnetic clutch comprising, in combination, coaxial driving and driven members, two coaxial clutch elements mounted for rotation respectively with said members and for relative axial movement, an annular pole ring mounted on one of said elements for movement therewith and adapted for direct bearing en. gagement with the other of said elements, friction facing means between said elements, and an electromagnet for effecting relative axial engagement between said elements.

13. An electromagnetic clutch comprising, in combination, coaxial driving and driven members, two coaxial friction disk clutch elements connected for rotation respectively with said members and having magnetic pole faces adapted for direct bearing engagement, one of said elements being axially stationary and the other of said elements being adapted for free axial floating movement, a stationary electromagnet for f attracting said pole faces into engagement, and

a detent having a limited axial lost motion connection with said last mentioned element and being in frictional engagement with one of said members.

14-. An electromagnetic clutch comprising, in '60 combination, coaxial driving and driven elements, two coaxial friction disk clutch elements connected for rotation respectively-to said elements and having opposed magnetic pole faces, an' electromagnet for attracting said pole faces, one of said elements being axiallystat'ionary and the other of said elements being axially movable and having a peripheral groove, and a split circular spring fitting freely in said groove and'resiliently engaging one of said members to provide a fric- 7 tional drag, said springbeing less in width than said groove. 1

15. An electromagnetic clutch comprising, in combination, coaxial rotary inner and outer members, a. cylindrical housing secured coaxially to said outer member, two friction disk clutch elements mounted within said housing and connected for rotation respectively with said members, and having opposed magnetic pole faces, one of said elements being axially stationary and the other of said elements being axially movable and formed with an outer peripheral groove, a split circular spring positioned in said groove and bearing frictionally against the interior of said housing, said groove being greater in width than said ring to permit a limited degree of lost motion, and means for securing said spring against rotation in said groove.

16. An electromagnetic clutch comprising, in combination, a stationary annular electromagnet having annular transfer poles in opposite ends, coaxial driving and driven members, a cage of non-magnetic material fixed on one of said members and extending through said electromagnet, said cage having longitudinal spline bars connected at one end by an annular internal fiange and at the other end by an annular external flange, two rings mounted within and concentrically of said electromagnet and said cage, and defining peripheral transfer pole faces respectively in opposed closely spaced relation to said first mentioned faces, one of said rings being positioned against said internal flange for rotation with said cage, the other of said rings being splined to said bars for axial movement, two clutch disks axially splined to said bars and positioned respectively against the adjacent faces of said rings, an intermediate clutch disk positioned between said two disks and axially splined to the other of said members, friction facings between said disks, and two working pole rings keyed for rotation with and separably positioned against the adjacent faces of said two disks for direct bearing engagement with opposite sides of. said intermediate disk, said rings and disks being axially removable from said cage through said external flange. v j

17. An electromagnetic clutch comprising, in combination, a stationary annular electromagnet having annular transfer poles in oppositeends, coaxial driving and driven members, a cage of non-magnetic material fixed on one of said members and extending through said electromagnet, said cage having longitudinal spline bars, two rings mounted within and concentrically of said electromagnet and said cage, and defining peripheral transfer pole faces respectively in opposed closely spaced relation to said first mentioned faces, stop means for one of said rings, the other of said rings being splined to said bars for axial movement, two clutch disks axially splined to said bars and positioned respectively against the adjacent faces of said rings, an intermediate clutch disk positioned between said two disks and axially splined to the other of said members, friction facings between said disks, and two working pole rings keyed for rotation with and positioned against the adjacent faces of said two disks for direct bearing engagement with opposite sides of said intermediate disk.

18. An electromagnetic clutch comprising, in combination, coaxial driving and driven members, an axially fixed clutch element, an axially movableclutch element secured for rotation with one of said members, a clutch element intermediate said first mentioned clutch elements and secured for rotation with and axial movement along the other of said members, and a stationary annular electromagnet encircling said elements,

said elements having pole faces in direct rubbing engagement and located in the path of flux of said electromagnet.

19. An electromagnetic clutch comprising, in combination, coaxial driving and driven members, an axially fixed friction clutch element, an axially movable friction clutch element secured for rotation with one of said members, a clutch ele-. ment intermediate said first mentioned clutch elements and secured for rotation with and axial movement along the other of said members, a stationary annular electromagnet encircling said elements, said elements having pole faces adapted to be in direct rubbing engagement and located in the'path of fiux of said electromagnet, and means for automatically limiting the range of movementof said movable element to a predetermined distance regardless of wear.

20. A clutch mechanism comprising, in combination, a friction disk clutch having a plurality of clutch elements movable axially into and out of engagement and including one axially fixed end element, a stop nut adjustably fixed in relation to said end element, an actuator for said clutch seated against said nut and having a rotary operating memmr, a ratchet wheel rigid with said nut, an oscillatory pawl in engagement with said wheel, and spaced stops on said operating member at opposite sides of said pawl for oscillating the latter, whereby said nut will be automatically adjusted relative to said end element to compensate for wear on said elements.

21. A clutch mechanism comprising, in combination, a. friction disk clutch having a plurality of clutch elements movable axially, into and out of engagement and including one axially fixed end element, a stop nut adjustably fixed in relation to said end element, an actuator for said clutch seated against said nut and having a rotary operating member, a ratchet wheel rigid with said nut and formed with a peripheral groove, a split circular spring positioned in said groove and formed with a pawl in engagement with said wheel, a lateral arm on said pawl and formed with oppositely facing spring abutments, and two spaced stops on said operating member at opposite sides of said arm for engagement respectively with said abutments to oscillate said pawl.

22. A clutch mechanism comprising, in combination, a friction disk clutch having a plurality of clutch elements movable axially into and out of engagement and including one axially fixed end element, a sleeve rigid with said end element, a stop nut threaded on said sleeve, an actuator for said clutch seated against said nut and having a rotary operating sleeve, a ratchet wheel rigid with said nut, a freely oscillatory pawl in engagement with said wheel and having a lateral projection, and two spaced stops on said operating sleeve for respectively engaging opposite sides of said projection to oscillate said pawl.

23. An end face ball cam actuator comprising, in combination, two coaxial elements having opposed end faces, means for limiting axial movement of one of said elements in one direction, two cam groovesspaced degrees apart in one of said faces and being arcuate about the axis of said elements and formed with an axial lead in one direction, two grooves spaced 180 degrees apart in the other of said faces and located in opposed cooperative relation to said cam grooves, two balls disposed in rolling engagement with said sets of grooves and being spaced 180 degrees apart to permit relative rocking movement'between said elements about a transverse axis, and

means for rotating said elements relatively to each other.

24. In a clutch mechanism, in combination,

two coaxial elements having opposed end faces,.

means for limiting axial movement of one of said elements in one direction, two cam grooves spaced 180 degrees apart in each of said faces and being arcuate about the axis of said elements, the sets of grooves being located in opposed cooperative relation and having axial leads in the same direction, two balls disposed in rolling engagement with said sets of grooves and being spaced 180 degrees apart to permit relative rocking movement between said elements about a transverse axis, and means for rotating said elements relatively to each other.

25. In a clutch mechanism, in combination, two

coaxial elements having opposed end faces, means for limiting axial movement of one of said elements in one direction, two hardened blocks spaced 180 degrees apart and inserted in each of said faces, each block being formed with a cam groove arcuate about the axis of said elements and having a stop at its leading end, the sets of grooves in said end faces being located in opposed cooperative relation and being inclined in the same direction relatively to said axis, two balls disposed in rolling engagement with said sets of grooves and being spaced 180 degrees apart when in engagement with said stops to permit relative rocking movement between said elements about a transverse axis, and means for rotating said elements relatively to each other.

26. In a clutch mechanism, in combination, two coaxial elements having opposed end faces, means for limiting axial movement of one of said elements in one direction, two cam grooves spaced 180 degrees apart in each of said faces, each cam groove being arcuate about the axis of rotation of said elements and being formed with a leading face portion having a relatively steep slope, with a stop at the leading end of said portion and with a trailing face portion having a relatively gradual slope, the sets of grooves in said end faces being located in opposed cooperative relation and having axial leads in the same direction, two balls disposed in rolling engagement with said sets of grooves and being spaced 180 degrees apart to permit relative rocking movement between said elements about a transverse axis, and means for rotating said elements relatively to each other.

2'7. An end face ball cam actuator comprising, in combination, three coaxial elements having two sets of opposed end faces, two grooves spaced 180 degrees apart in each of one set of end faces, the sets of grooves being uniformly arcuate about the axis of said elements and being located in opposed cooperative relation, two balls disposed in bearing engagement with said sets of grooves and spaced 180 degrees apart to permit relative rocking movement of the associated elements about a transverse axis, two cam grooves spaced 180 degrees apart in each of the other set of end faces and spaced degrees from said first mentioned grooves, the sets of cam grooves being uniformly arcuate about said axis and being located in opposed cooperative relation, two balls disposed in bearing engagement with said sets of cam grooves and being spaced degrees apart to permit relative rocking movement between the associated elements about a transverse axis perpendicular to said first mentioned transverse axis, and means for rotating the intermediate element relative to the end elements.

28. In a clutch mechanism, in combination, three coaxial elements having two sets of opposed end faces, two grooves spaced 180 degrees apart in each of one set of end faces, the sets of grooves being'uniformly arcuate about the axis of said elements and being located in opposed cooperative relation, two balls disposed in bearing engagement with said sets of grooves and spaced 180 degrees apart to permit relative rocking movement of the associated elements about a transverse axis, two graduated cam grooves spaced 180 degrees apart in each of the other set of end faces and spaced 90 degrees from said first mentioned grooves, said cam grooves being uniformly arcuate about said axis and each being formed with a leading face portion having a relatively 'steep slope, with a stop shoulder at the leading end of said portion, and with a trailing .face portion having a relatively gradual slope,

the sets of cam grooves being located in opposed cooperative relation and having axial leads in the same direction, two balls disposed in bearing engagement with said sets of cam grooves and being spaced 180 degrees apart to permit relative rocking movement between the associated elements about a transverse axis perpendicular to said first mentioned transverse am's, and means for rotating the intermediate element relative to the end elements.

29. In a clutch mechanism, in combination, a sleeve, a nut threaded on said sleeve, an outer concentric sleeve having an internal peripheral flange with opposite end faces, a ring interposed between said nut and said flange and bearing against said nut and having an end face opposed to said flange, means for preventing rotation of said ring relative to said nut, two grooves spaced 180 degrees apart in each of the adjacent end faces of said flange and said ring, each groove being arcuate about the axis of said flange, two balls disposed in bearing engagement with said sets of grooves and being spaced 180 degrees apart, a ring having an end face in opposed relation to the other end face of said flange and normally being secured against rotation, two cam grooves spaced 180 degrees apart in each of said last mentioned end faces, said cam grooves being arcuate about the axis of said flange and being located in opposed cooperative relation, two balls disposed in bearing engagement with said sets of cam grooves and being spaced 180 degrees apart and 90 degrees from said first mentioned balls, and means for rotating said flange.

1 HQWARD D. COLMAN. 

